Part of Lesson Plan: **Ignition systems types (updated) by Sergio Marquez

Activity Overview / Details

While lecturing students will follow on text book (Thomson Delmar Learning, "Automotive Technology: A Systems Approach," 4th edition), pages 597-598.

I will explain that ignition timing refers to the time spark occurs and the position of the # 1 cylinder piston in relation to crankshaft rotation this is called base ignition timing.  Explain that when the two marks line up, this is called TDC (Top Dead Center) or 0 degrees, on the #1 cylinder compression stroke. Refer to fig.24-2 page #597. Timing marks are typically located in the front of the engine on the timing cover and crankshaft pulley. From TDC or 0 degrees to the left of engine rotation is referred to BTDC (Before Top Dead Center), to the right of TDC or 0 degrees is referred as ATDC (After Top Dead Center). Refer to fig. 24-2 page #597 and fig. 25-36 page #647.

I will explain that firing order, referring to the order that each cylinder is fired after the #1 cylinder, ex. if the base timing for an engine is 8 degrees BTDC then all cylinders will fire at 8 degrees when each one come up on there compression stroke, in a firing order. Refer to fig. 24-3 page 598.